Vacuum pump



2 Sheets-Sheet l Cyrus /awag z/vyaac/ Arran/5K5..

Sept. 18, 1928.

c. H. HAPGooD VACUUM PUMP Filed Nov. so, 192s llll Il septl 1s, `192s.

c. H. HAPGQD Filed NOV 30, 1926 2 Sheets-Sheet 2 'MWF/rra@ mm W1/Mq l Patented Sept. 18, 1928.-

UNITED sTATEs PATENT OFFICE.

cYRUs HOWARD HAPGooD, or NUTLEY, NEW JERSEY,

ASSIGNOR T THE DE LAVAL SEPARA'IOR COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

VACUUM PUMP.

Application med November 3o, 192e'. serial No. 151,659.

A highly efficient type of vacuum pump comprises a housing, a hollow rotor within and eccentric to the housing, an air inlet port to, and an airoutletj port from, the air 5 space between housing and rotor, shdable vanes carried by the rotor and arranged radially to the rotor shaft and which extend into said air space and contact with the housing during the rotation of the rotor, oil reservoirs open to the atmosphere withln the end heads of thel housing and adaptedto receve'drips from the bearings and which are freely open to the interior of the rotor so as to allow oil to freely iiow thereinto and maintain a sealing body of oil therein, an oil se 'arator in the air discharge passage, and oil) passages from the oil separator to the bearings and to the .interior of the rotor. Such a vacuum pump is shown in the Leitch Patent N o. 1,367,554', dated February 8, 1921, and the Hall Patent No. 1,374,650, dated April 12, 1921.

In the operation of such a pump, conditions arise which cause oil to 'escape from the pump around the"bearings, thereby causing waste. Among such causes are variations from the normal air pressure conditions within the pump. For example, in the normal operation of the pump, when used as a part of a milking machineA outfit, the absolute pressure at the inlet port to the air compression space between housing and rotor may be fifteen inches mercur While at the outlet port from this space the'pressure is close to atmospheric. If any condition should arise that increases the absolute pressure at the inlet, as, for instance, if the -teat cups drop off the cow and the absolute-pressure at the inlet 'consequently jumps to atmospheric ressure, the pressure at the outlet port of the housing will rise to two atmospheres. 'This pressure forces air between-thev ends of the rotor and the adjacent' housing capsinto the interior of the rotor, whencel it freely escapes into the oil reservoirs,'causing oil to be blown over the edge of the bearing surrounding the chamber in the end head of the housing.

The oil losses arising during normal operation and from abnormal, but recurring, operative conditions have been assumed to be due to back pressure at the discharge of the pump operating through oil passages communicating with the interior of the rotor: and, for the purpose of avoiding the supposed effects of such back pressure, such passages have been restricted to the greatest possible degree; wlthv the result, however, of accentuat- .ing, instead of remedying, the objectionable pumpto atmosphere is relatively free. The l former provision limits the inflow of compressed air from the interior of the rotor to the oil reservoirs, while by means of the latter provision, the interior of the rotor communicates with the atmosphere so freely that no opportunity for building up substantial air pressure in the reservoirs or the interior of the rotor is afforded. By reconstructing and simplifying the bearings, it has been found possible to reduce the diameter of the end axial opening in the housing and thereby raise the lower edge of this opening further above the oil level in the reservoirs, thereby still further reducing the likelihood of escape of' oil at this point. j

A vpreferred embodiment of the invention is shown in the drawings, in which Fig. 1 is a longitudinal sectional View of the pump.

Fig. 2 is a cross-section through the pump on the line 2-2 of Fig. 1.

Fig. 3 is a cross-section lthrough the pump on the line 3-3 of Fig. 1.

Rotor a is mounted on a shaft b carried by bearings c, c' on the end heads d and e of housing f. Between the shell of therotor and the wall of the housing isthe air compression space. Rotor a has slots through which wings Aor vanes g extend into cont-act with the inner wall of the housing, these vanes sliding toward and from the haft in the rotation of the. rotor, which'is eccentrically disposed with relation to the housing. L is the inlet port to the air compression space between rotor and housing and z' the outlet port from said space.

end heads that communicate with the interior of the rotor, the reservoirs are connected by a passage extending through the lower part of t-he housing; or, in other words, the housing is (preferably) so shaped as to allord a single formed in one of the end heads of the housing. Instead of restricting the flow of air be tween the discharge jand the interior of the rotor, the clearances are made so large as to form relatively unrestricted passages n so as to insure the maintenance, under allr condi tions, of pressure inside the rotor corresponding to that at the discharge j. Y.

The end head d of the housing is provided with an opening concentric to the axis, through which opening projects the hub of a pulley lo, affording an annular space between the housing and the pulley hub. The lower edge of this annular space 1s a substantial distance above the normal oil level within the housing. This factor, however, is of minor importance in preventing oil leakage. The ma]orfactors are the yprovision of a relatively unrestricted passage between the interior of the rotorand the air discharge j from the' housing, and, secondarily, the provisionof a relatively restricted opening between the interior of the rotor and the oil reservoir lc.4

Owing' to the free outflow of air at the discharge j, no substantial pressure can build up therein notwithstanding the building up of pressure in the air compression space ot the pump. While air pressure tends to build up in the interior oi ther'otor, such ressure is capable of being relieved through oth opening m and passages'n. The unrestricted character of the passages n permits free outflow of air from the interior of the rotor and prevents any substantial pressure bein built up therein and consequently there can e no substantial inflow of compressed air into the reservoir. Therefore,the air pressure in the reservoir can never rise substantially above n'ormal atmospheric pressure and hence no conrditions can exist which tends to cause oil leakage from the reservoir. v

The gear casings outside the housing freely communicate through opening 1' with the atmosphere and through passage p with the res- To automatically'supply the reservoir Iwith oil and maintain the level of oil therein, I .provide aperforated cup t extending into the oil reservoir space within the housing. Ex-

tending through the bottom of the cup is an oil discharge tube u and an air admission tube v. Oil tube uis relatively short, but extends In operation, the level of oil in the reservoir cannot fall substantially below the lower end of tube fv, because as soon as that occurs to a. slight extent, air escapes from the reservoir through pipe 'v into the air space in the bottle above the 011, and the air pressure therein immediately acts to expel oil from the into the hollow 1nterior oftheirotor and intov 'the air space between rotor and housing, anl

oil reservoir in the housing, the housing bein provided with an inlet and an outlet to sai air space, and a discharge to atmosphere communicatmg with sa1d outlet, of means providing a relatively unrestricted passage for air between the hollowT interior of the rotor and said discharge, there being an opening between the oil reservoir and the hollow interior of the rotor allowing flow of oil from reservoir to rotor, said opening being relaltively restrictedto limit the flow of air therethrough relative to the flow of air between the hollow-interior of the rotor and the discharge. 2. In a vacuum pump, the combination bottle through pipe u and raise the level of oil in the with a housing, a hollow rotor eccentrically4 disposed therein, slidable vanes extendin'g into the hollow interior of the rotorand into the airspace between rotor and housing, the housinfr having an oil reservoir extendingbeneath the rotor and on opposite sides thereof, the housing having also an inlet and an outlet to' said air spaceand a discharge to atmosp here communicating with said outlet, .of

means providingfa relatively unrestricted air vpassage between the hollow interior of rotor and said discharge, there being an open ing in one of the end headsof the housing 'afflording a relatively restricted opening for o1l and air flow between the reservoir and the hollow interior of the rot-or.

In testimony of which lnvention, I have hereunto set'my hand, at city of New York,

on this 12th dayof-November, 1926.

CYRUS HOWARD HAPGooD. 

